How could the Cassini spacecraft potentially 'contaminate' a moon during its mission?

• A. By emitting high levels of radiation that alter the moon's atmosphere
• B. By removing all existing organic molecules from the moon
• C. By causing the moon to lose its gravitational field
• D. By introducing Earth microbes to the moon's surface during an unintended crash landing

Answer: (D)

Verified step by step guidance

1. Understand the concept of planetary protection, which aims to prevent biological contamination of other celestial bodies by Earth organisms during space missions.
2. Recognize that spacecraft like Cassini carry microbes from Earth that can survive the harsh conditions of space and potentially contaminate extraterrestrial environments if they come into direct contact.
3. Analyze the scenario where Cassini could unintentionally crash land on a moon, thereby depositing Earth microbes onto the moon's surface.
4. Evaluate why other options such as emitting radiation, removing organic molecules, or affecting the moon's gravitational field are not realistic mechanisms of contamination by the spacecraft.
5. Conclude that the primary concern for contamination is the introduction of Earth microbes to the moon's surface during an unintended crash landing, which could interfere with the moon's natural state and future scientific investigations.